A collaborative project involving Dr. Edwin W. Salzman of Harvard Medical School and Professors Edward W. Merrill and David Waugh of M.I.T. will be devoted to design and development of thromboresistant materials and to exploration of basic aspects of interaction of blood with artificial surfaces. Dr. Salzman's laboratory will bear primary responsibility for biological evaluation of materials fabricated by Professor Merrill and associates in a systematic assessment of the interaction of potentially nonthrombogenic materials with blood, with emphasis on the influence of well characterized model surfaces on plasma coagulation and alterations of platelets. Professor Waugh will examine the relation of adsorption of plasma proteins and subsequent events to the surface chemistry of the substrate materials and will correlate these observations with the experiments of Professors Salzman and Merrill involvng the same materials. An attempt will be made to develop a theoretical framework relating these phenomena to surface chemistry in order, ultimately, to guide development of more effective thromboresistant materials. The project will also include basic studies of the biochemistry of blood platelets, particularly in regard to the mechanisms of platelet activity induced by contact with artificial surfaces.